Reciprocating downhole pump

ABSTRACT

A reciprocating pump for use in a wellbore is disclosed. The pump includes a fluid directing apparatus for directing fluid in and out of the pump, the fluid directing apparatus having an inlet disposed in a sidewall of the fluid directing apparatus and an outlet. The pump also includes a piston disposed in a fluid housing and a piston driving apparatus for reciprocating the piston in the fluid housing to cause fluid to be pulled in and out of the fluid directing tool. A method of using the reciprocating pump is also disclosed. The pump is placed in to the wellbore in an area where fluid is desired to be pumped out of the wellbore. Once positioned in the wellbore, the pump is operated to remove fluid from the wellbore.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a conversion of U.S. Provisional Application having U.S. Ser. No. 62/010,159, filed Jun. 10, 2014, which claims the benefit under 35 U.S.C. 119(e), the disclosure of which is hereby expressly incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND OF THE DISCLOSURE

1. Field of the Invention

The present disclosure relates to a reciprocating downhole pump that forces fluid to the surface from down in a wellbore.

2. Description of the Related Art

Conventional sucker rod pumps used in the oil and gas industry have proven to be very reliable pumps for lifting fluid from the wellbore. Typically, these pumps are reciprocated by a counterbalanced mechanism on the surface, which lift rods attached to a plunger in the pump. These rods are heavy and due to the reciprocating action cause wear on the rods and the tubing. In deviated wellbores, the rods will wear holes in the tubing requiring remedial work to replace the tubing joints with holes. Rods can also wear requiring additional remedial work. In deep wells the rods will stretch and the effectiveness of the pump can be reduced due to the stretching and contracting of the rods. The surface drive mechanism and rod configuration can be tuned to reduce this dynamic effect from the reciprocating action, but can reduce the overall efficiency of the pumps operation.

Accordingly, there is a need for a downhole pump that can be reciprocated without using rods that extend from the surface to the pump.

SUMMARY OF THE DISCLOSURE

The present disclosure is directed towards a reciprocating pump for use in a wellbore. The pump includes a fluid directing apparatus for directing fluid in and out of the pump, the fluid directing apparatus having an inlet disposed in a sidewall of the fluid directing apparatus and an outlet. The pump also includes a piston disposed in a fluid housing and a piston driving apparatus for reciprocating the piston in the fluid housing to cause fluid to be pulled in and out of the fluid directing tool.

The present disclosure is also directed toward a method of using the reciprocating pump. The pump is placed in to the wellbore in an area where fluid is desired to be pumped out of the wellbore. Once positioned in the wellbore, the pump is operated to remove fluid from the wellbore.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a downhole pump constructed in accordance with one embodiment of the present disclosure.

FIGS. 2A-2D show a perspective view of a portion of the downhole pump constructed in accordance with the embodiment shown in FIG. 1.

FIG. 3 is a cross-sectional view of another embodiment of the downhole pump constructed in accordance with the present disclosure.

FIG. 4 is a cross-sectional view of a portion of the downhole pump shown in FIG. 3.

FIG. 5 is a cross-sectional view of another portion of the downhole pump shown in FIG. 3.

FIG. 6 is a cross-sectional view of yet another portion of the downhole pump shown in FIG. 3.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure relates to a downhole reciprocating pump 10 that forces fluid to the surface from down in a wellbore. Generally, the reciprocating pump 10 includes a fluid directing apparatus 12 for controlling fluid entering and exiting the pump 10, a piston 14 to pull fluid in and force fluid out of the pump 10, and a piston driving apparatus 16 for forcing the piston 14 towards and away from the fluid directing apparatus 12. The pump 10 can also include a fluid housing 18 where the piston 14 travels therein and where fluid drawn into the pump 10 via the fluid directing apparatus 12 can be temporarily stored before the fluid is forced out of the pump 10, through the fluid directing apparatus 12 and to the surface. Additionally, the pump 10 can include a rod 20, or similar device, to connect the piston 14 to the piston driving apparatus 16. The rod 20 can be attached, supported by or connected to the piston driving apparatus 16 via any manner known in the art.

The piston driving apparatus 16 can be any type of device known in the art capable of reciprocatingly driving the piston 14, via the rod 20, toward and away from the fluid directing apparatus 12. In one embodiment shown in FIG. 1, the piston driving apparatus 16 can include a housing 22 and a rotatable screw 24 disposed therein. The housing 22 can also be a hydraulic cylinder for the piston driving apparatus 16 in various embodiments described herein. The screw 24 can be a self reversing screw that has a gear ratio reduction that can be turned to provide the reciprocating motion to the piston 14. The screw 24 can be operated in an oil bath and run/turned by an electric motor 26. The screw 24 can be operated and designed to provide any length of travel to the piston 14 and any rate at which it is desirable for the piston 14 to reciprocate. In addition to the electric motor 26, the pump 10 described herein can be powered by a hydraulic motor or a triplex pump from the surface of the well.

The piston driving apparatus 16 further includes at least one blade 28 having a dog 30 attached thereto. The blade 28 is designed to fit within and be guided by an upward directing channel 32 and a downward directing channel 34 disposed in the screw 24. The upward directing channel 32 can be a helical shaped channel that forces and guides the blades 28 (and thus the dogs 30) in the uphole direction when the screw 24 is rotating. The downward directing channel 34 can be a helical shaped channel that forces and guides the blades 28 (and thus the dogs 30) in the downhole direction when the screw 24 is rotating. The screw 24 can have a first reversing portion 36 to cause the blade 28 to transition from the upward directing channel 32 to the downward directing channel 34. Similarly, the screw can include a second reversing portion 38 to cause the blade 28 to transition from the downward directing channel 34 to the upward directing channel 32. It should be understood and appreciated that the upward directing channel 32 and the downward directing channel 34 will intersect as they wind around and travel the length of the screw 24.

Furthermore, the piston driving apparatus 16 includes a sleeve 40 disposed around the screw 24 and slidably disposed in the housing 22 of the piston driving apparatus 16. The sleeve 40 is supported by the rod 20 via an adapter 42 on one end of the sleeve 40. The other end of the sleeve 40 has at least one radial directed opening 44 disposed therein to receive at least one of the dogs 30 attached to the at least one blade 28. The dogs 30 are rotatably disposed within the openings 44 so that the blades 28 and dogs 30 are allowed to rotate when they are forced to rotate by the upward directing channel 32 and the downward directing channel 34 as the screw 24 rotates.

Referring now to FIGS. 2A-2D, shown therein is the screw 24 with the blade 28 disposed in various positions within the upward directing channel 32 and the downward directing channel 34. In FIGS. 2A-2D it should be understood that lower part of the screw 24 (as oriented on the drawing sheet) is rotating away from the drawing sheet and the upper part of the screw (as oriented on the drawing sheet) is rotating into the drawing sheet. FIG. 2A shows the blade 28 in the first reversing portion 36 of the screw 24 where the blade 28 is being transitioned from traveling in the upward directing channel 32 (going in the uphole direction) to traveling in the downward directing channel 34 (going in the downhole direction). FIG. 2B shows the blade 28 disposed in the upward directing channel 32 as the screw 24 rotates.

Furthermore, FIG. 2C shows the blade 28 in the second reversing portion 38 of the screw 24 where the blade 28 is being transitioned from traveling in the downward directing channel 34 (going in the downhole direction) to traveling in the upward directing channel 32 (going in the uphole direction). FIG. 2D shows the blade 28 disposed in the downward directing channel 34 as the screw 24 rotates. From the position shown in FIG. 2D, the blade 28 would then continue in the downward directing channel 34 until the blade 28 reached the first reversing portion 36 of the screw 24 as shown in FIG. 2A.

The upward directing channel 32 and the downward directing channel 34 have a pitch that can be altered depending on the desired design of the pump 10. In other words, either the upward directing channel 32 or the downward directing channel 34 can have a pitch where the blades 28/dogs 30 travel a particular distance along the length of the screw 24 for every full revolution of the screw 24. For example, the blades 28/dogs 30 can travel one inch, two inches, four inches, etc. in the uphole or downhole direction for every revolution of the screw 24. It should be understood that the pitch of the upward directing channel 32 and the pitch of the downward directing channel 34 can be similar or different.

In another embodiment, the self reversing screw 24 can be a ball reverser wherein balls or bearings are used in place of the blades 28/dogs 30. It should be understood and appreciated that the upward directing channel 32 and the downward directing channel 34 would be sized and shaped to work with the balls or bearings of the ball reverser screw.

In use, the electric motor 26 (or some other source of rotation) rotates the screw 24. If the blade 28 is disposed within the upward directing channel 32 as the screw 24 is rotated, the blade 28 is forced upward (or uphole) in the pump 10. As the blade 28 and the dog 30 are forced upward, the sleeve 40 and adapter 42 are moved in the uphole direction, which forces the rod 20 and piston 14 upward and expels fluid from the fluid housing 18, through the fluid directing apparatus 12 and out of the pump 10. Conversely, if the blade 28 is disposed within the downward directing channel 34 as the screw 24 is rotated, the blade 28 is forced downward (or downhole) in the pump 10. As the blade 28 and the dog 30 are forced downward, the sleeve 40 and adapter 42 are moved in the downhole direction, which pulls the rod 20 and piston 14 downward and pulls fluid through the fluid directing apparatus 12 and into the fluid housing 18.

Furthermore, if the blade 28 is positioned in the downward directing channel 34 as the screw 24 is rotating, the blade 28, and ultimately the piston 14, will travel downhole in the pump 10 until the blade 28 reaches the second reversing portion 38 of the screw 24 wherein the blade 28 will be redirected toward the upward directing channel 32 in the screw 24 as the screw 24 is rotated. Likewise, the blade 28, now positioned in the upward directing channel 32, is forced upward in the pump 10. Due to the blade's 28 relationship to the piston 14, the piston 14 is also forced upward in the pump 10. The blade 28 continues traveling upward in the pump 10 as the screw 28 rotates until the blade 28 reaches the first reversing portion 36 of the screw 24. Once the blade 28 reaches the first reversing portion 36 of the screw 24, the rotation of the screw 24 will force the blade 28 back into the downward directing channel 34.

In another embodiment shown in FIGS. 3-6, the piston driving apparatus 16 includes a hydraulic piston apparatus 46 to drive the piston 14 of the pump 10. The hydraulic piston apparatus 46 can be driven by any means known in the art. In one embodiment, the hydraulic piston apparatus 46 can be attached to the rod 20 and include a piston head 48 and a rod element 50. The fluid housing 18 is separated from the housing 22 of the piston driving apparatus 16 by a separation element 52 to prevent pumped fluid from the well in the fluid housing 18 from mixing with hydraulic fluid in the housing 22 of the piston driving apparatus 16. The separation element 52 is designed such that the rod 20 is slidably disposed therein. The piston driving apparatus 16 further includes a secondary housing 54 separated from the housing 22 via a second separation element 56. Similarly, the second separation element 56 is designed such that the rod element 50 of the hydraulic piston apparatus 46 is slidably disposed therein.

The rod element 50 of the hydraulic piston apparatus 46 has a passageway 58 disposed therein that is in fluid communication with the secondary housing 54 of the piston driving apparatus 16 on one end of the passageway 58 and in fluid communication with one end of another passageway 60 disposed in the piston head 48. The passageway 60 disposed in the piston head 48 is in fluid communication with the housing 22 of the piston driving apparatus 16 between the piston head 48 and the separation element 52.

The second separation element 56 includes a first passageway 64 disposed axially therethrough for permitting the rod element 50 of the hydraulic piston apparatus 46 to be slidably disposed therein. The second separation element 56 also includes a second passageway 66 wherein hydraulic fluid is permitted to flow therethrough. The second passageway 66 fluidically connects the housing 16 and the secondary housing 54 of the piston driving apparatus 16. The pump 10 can also include a conduit 68 disposed in the secondary housing 54 of the piston driving apparatus 16 that fluidically connects a hydraulic fluid directing apparatus 70, such as an electric motor or an automatic reversing hydraulic circuit, with the second passageway 66 disposed in the second separation element 56.

In operation, the hydraulic fluid directing apparatus 70 forces hydraulic fluid from the secondary housing 54 into the passageway 58 disposed in the rod element 50 of the hydraulic piston apparatus 46. From the passageway 58, the hydraulic fluid is then forced through the passageway 60 disposed in the piston head 48 and into the housing 22 of the piston driving apparatus 16 between the piston head 48 and the separation element 52. The hydraulic fluid being forced into the housing 22 between the piston head 48 and the separation element 52 forces the hydraulic piston head 48 away from the separation element 52 (downhole direction), which pulls the piston 14 away from the fluid directing apparatus 12 via the rod's 20 connection to the piston 14 and the hydraulic piston apparatus 46.

Conversely, the hydraulic fluid directing apparatus 70 can force hydraulic fluid through the conduit 68 and the second passageway 66 in the second separation element 56. From the second passageway 66 in the second separation element 56, the hydraulic fluid flows into the housing 22 of the piston driving apparatus 16 between the piston head 48 of the hydraulic piston apparatus 46 and the second separation element 56. The fluid flowing into the housing 22 of the piston driving apparatus 16 between the piston head 48 of the hydraulic piston apparatus 46 and the second separation element 56 forces the hydraulic piston head 48 away from the separation element 56 (uphole direction), which drives the piston 14 toward the fluid directing apparatus 12 via the rod's 20 connection to the piston 14 and the hydraulic piston apparatus 46.

Shown in more detail in FIG. 6, the fluid directing apparatus 12 can be disposed on an uphole side of the pump 10. The fluid directing apparatus 12 includes a fluid directing housing 72 attached to the fluid housing 18 that encapsulates the piston 14. The fluid directing apparatus 12 includes an inlet 74 disposed in a sidewall 76 of the fluid directing housing 72 for permitting fluid to enter the fluid directing apparatus 12 and ultimately the fluid housing 18. The fluid directing apparatus 12 also includes an outlet 78 disposed therein to permit fluid to travel from the fluid housing 18 through the fluid directing apparatus 12 and out of the pump 10. In one embodiment, the outlet 78 is disposed in an end portion 80 of the pump 10 so that the fluid exiting the pump 10 can ultimately enter a tubing string attached to the fluid directing apparatus 12 or pump 10.

The fluid directing apparatus 12 has a first fluid passageway 82 and a second fluid passageway 84. The first fluid passageway 82 fluidically connects the inlet 74 and the fluid housing 18. The second fluid passageway 84 fluidically connects the outlet 78 and the fluid housing 18. The first fluid passageway 82 has a first seat 86 and a first fluid blocking member 88 disposed therein to be able to engage the first seat 86 and prevent fluid from flowing from the fluid housing 18, through the fluid directing apparatus 12 and out the inlet 74. The second fluid passageway 84 has a second seat 90 and a second fluid blocking member 92 to be able to engage the second seat 90 and prevent fluid from flowing from inside the tubing string and into the fluid housing 18. The first and second fluid blocking members 88 and 92 can be any size and shape capable of blocking fluid from flowing in the directions described herein. Examples of fluid blocking members 88 and 92 include, but are not limited to, balls, darts, and the like.

In another embodiment, the fluid directing apparatus 12 includes a first expansion device 94 disposed in the first fluid passageway 82 and a second expansion device 96 disposed in the second fluid passageway 84. The first expansion device 94 is secured on one end 98 to a part of the first fluid passageway 82 and contacts the first fluid blocking member 88 to force the first fluid blocking member 88 in to the first seat 86. The second expansion device 96 is secured on one end 100 to a part of the second fluid passageway 84 and contacts the second fluid blocking member 92 to force the second fluid blocking member 92 into the second seat 90.

In another embodiment, the first fluid passageway 82 can include a first stop element 102 disposed therein to engage with the end 98 of the first expansion device 94 to prevent the first end 98 of the first expansion device 94 from moving in the first fluid passageway 82 in the direction of the stop element 102. Additionally, the second fluid passageway 84 can include a second stop element 104 disposed therein to engage with the end 100 of the second expansion device 96 to prevent the first end 100 of the second expansion device 96 from moving in the second fluid passageway 84 in the direction of the second stop element 104. It should be understood and appreciated that the first and second stop elements 102 and 104 can be designed such that fluid can flow therethrough.

The first and second expansion devices 94 and 96 are designed such that fluid is permitted to flow by or through and are compressible enough to permit fluid to flow between the fluid blocking members 88 and 92 and the corresponding seats 86 and 90 when the piston 14 forces fluid in a particular direction. In one embodiment, the first and second expansion devices 94 and 96 can be springs.

In use, the piston 14 is retracted away from the fluid directing housing 72 as described herein and fluid is pulled into the inlet 74 of the fluid directing housing 72 and into the first fluid blocking member 88. The first fluid blocking member 88 is forced away from the first seat 86 and the first expansion device 94 is compressed allowing fluid to flow through the first fluid passageway 82 and into the fluid housing 18. The piston 14 can then be forced back toward the fluid directing housing 72 as described herein, which forces the fluid into the second fluid passageway 84. The fluid then contacts the second fluid blocking member 92 and forces the second fluid blocking member 92 away from the second seat 90 and compresses the second expansion device 96. The fluid then flows between the second seat 90 and the second fluid blocking member 92 and past the second expansion device 96, out the outlet 78 in the fluid directing housing 72 and into the tubing string.

Various hydraulic drives have been described herein to rotate the screw 24 or reciprocate the hydraulic piston apparatus 46, such as the electric motor 26, a hydraulic motor, a triplex pump operated at the surface of a well. These hydraulic drives can be operated downhole or at the surface of the well. It should be understood that any type of hydraulic drive can be used to rotate the screw 24 or reciprocate the hydraulic piston apparatus 46.

In a further embodiment of the present disclosure, an electric drive can also be incorporated with the hydraulic drives to control the speed of the hydraulic drives. The electric drives can have variable frequencies to vary the speed of the screw 24 rotation and the hydraulic piston apparatus 46 reciprocation so that various pumping rates can be achieved. The electric drives can be submersible and placed in the wellbore with the pump to drive the screw or hydraulic motor.

From the above description, it is clear that the present disclosure is well adapted to carry out the objectives and to attain the advantages mentioned herein as well as those inherent in the disclosure. While presently preferred embodiments have been described herein, it will be understood that numerous changes may be made which will readily suggest themselves to those skilled in the art and which are accomplished within the spirit of the disclosure and claims. 

What is claimed is:
 1. A reciprocating downhole pump for use in a wellbore, the pump comprising: a fluid directing apparatus for directing fluid in and out of the pump, the fluid directing apparatus having an inlet disposed in a sidewall of the fluid directing apparatus and an outlet; a piston disposed in a fluid housing; and a piston driving apparatus for reciprocating the piston in the fluid housing to cause fluid to be pulled in and out of the fluid directing tool.
 2. The pump of claim 1 wherein the piston driving apparatus is a continuous self reversing screw disposed in a housing that can be designed to provide a specific length of travel and reciprocation rate of the piston, the screw having a downward directing channel and an upward directing channel disposed thereon.
 3. The pump of claim 2 wherein the piston driving apparatus is operated by a hydraulic drive disposed downhole or at a surface of the wellbore, the hydraulic drive can be an electric motor, a hydraulic motor or a triplex pump.
 4. The pump of claim 1 wherein the piston is driven by a hydraulic piston driving apparatus.
 5. The pump of claim 4 wherein the hydraulic piston driving apparatus comprises: a hydraulic piston apparatus disposed in a primary housing and connected to the piston via a rod, the hydraulic piston apparatus having a piston head and a rod element extending therefrom; and a hydraulic fluid driving apparatus for forcing fluid in two directions through the hydraulic piston driving apparatus to force the hydraulic piston apparatus in the uphole and downhole directions.
 6. The pump of claim 5 further comprising: a first separation element that separates the fluid housing from the primary housing of the hydraulic piston driving apparatus, the first separation element having a passageway disposed therein to permit the rod to slide therein; and a second separation element that separates the primary fluid housing from a secondary fluid housing of the hydraulic piston driving apparatus, the second separation element having a first passageway disposed therein to permit the rod element of the hydraulic piston apparatus to slide therein.
 7. The pump of claim 6 wherein the second separation element further includes a second passageway disposed therein to permit hydraulic fluid to be pumped therethrough.
 8. The pump of claim 7 wherein the hydraulic piston driving apparatus further includes a conduit disposed in the secondary fluid housing to direct hydraulic fluid from the hydraulic fluid directing apparatus into the second passageway disposed in the second separation element to permit hydraulic fluid to flow into the primary fluid housing between the piston head and the second separation element.
 9. The pump of claim 8 wherein the piston head has a passageway disposed therein in fluid communication with another passageway disposed in the rod element of the piston head to permit fluid to flow from the secondary fluid housing to the primary fluid housing between the piston head and the first separation element.
 10. The pump of claim 2 wherein the pump further comprises: a sleeve slidably disposed within the housing and around the screw, the sleeve has at least one radially directed opening disposed in a lower end of the sleeve; and a blade supported by the sleeve to engage the upward directing channel and the downward directing channel.
 11. The pump of claim 10 wherein the pump further comprises a dog that is attached to the blade and is rotatably disposed within the radially directed opening in the sleeve.
 12. The pump of claim 3 further comprising an electric drive having variable frequencies to vary the speed at which the hydraulic drives operate the piston driving apparatus.
 13. A method, the method comprising: placing a pump into a wellbore in an area where fluid is desired to be pumped out of the wellbore, the pump comprising: a fluid directing apparatus for directing fluid in and out of the pump, the fluid directing apparatus having an inlet disposed in a sidewall of the fluid directing apparatus and an outlet; a piston disposed in a fluid housing; and a piston driving apparatus for reciprocating the piston in the fluid housing to cause fluid to be pulled in and out of the fluid directing tool; and operating the pump to remove fluid from the wellbore.
 14. The method of claim 13 wherein the piston driving apparatus is a self reversing continuous screw that can be designed to provide a specific length of travel and reciprocation rate of the piston, the screw having a downward directing channel and an upward directing channel disposed thereon.
 15. The method of claim 14 wherein the piston driving apparatus is operated by a hydraulic drive disposed downhole or at a surface of the wellbore, the hydraulic drive can be an electric motor, a hydraulic motor or a triplex pump.
 16. The method of claim 13 wherein the piston is driven by a hydraulic piston driving apparatus.
 17. The method of claim 16 wherein the hydraulic piston driving apparatus comprises: a hydraulic piston apparatus disposed in a primary housing and connected to the piston via a rod, the hydraulic piston apparatus having a piston head and a rod element extending therefrom; and a hydraulic fluid driving apparatus for forcing fluid in two directions through the hydraulic piston driving apparatus to force the hydraulic piston apparatus in the uphole and downhole directions.
 18. The method of claim 17 further comprising: a first separation element that separates the fluid housing from the primary housing of the hydraulic piston driving apparatus, the first separation element having a passageway disposed therein to permit the rod to slide therein; and a second separation element that separates the primary fluid housing from a secondary fluid housing of the hydraulic piston driving apparatus, the second separation element having a first passageway disposed therein to permit the rod element of the hydraulic piston apparatus to slide therein.
 19. The method of claim 18 wherein the second separation element further includes a second passageway disposed therein to permit hydraulic fluid to be pumped therethrough.
 20. The method of claim 19 wherein the hydraulic piston driving apparatus further includes a conduit disposed in the secondary fluid housing to direct hydraulic fluid from the hydraulic fluid directing apparatus into the second passageway disposed in the second separation element to permit hydraulic fluid to flow into the primary fluid housing between the piston head and the second separation element.
 21. The method of claim 20 wherein the piston head has a passageway disposed therein in fluid communication with another passageway disposed in the rod element of the piston head to permit fluid to flow from the secondary fluid housing to the primary fluid housing between the piston head and the first separation element.
 22. The method of claim 14 wherein the pump further comprises: a sleeve slidably disposed within the housing and around the screw, the sleeve has at least one radially directed opening disposed in a lower end of the sleeve; and a blade supported by the sleeve to engage the upward directing channel and the downward directing channel.
 23. The method of claim 22 wherein the pump further comprises a dog that is attached to the blade and is rotatably disposed within the radially directed opening in the sleeve.
 24. The method of claim 15 further comprising an electric drive having variable frequencies to vary the speed at which the hydraulic drives operate the piston driving apparatus. 